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Old 09-09-2011, 03:28 PM   #1
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A few questions.


1.) Can refrigerant go flat in a system, say if a system has been off for six months? Can it sit idle for that period of time and then once started show low pressures even once stabilized?

2.) What's the minimum voltage required to start and run an evaporator 208/240 volt blower motor? I came across a furr down that had 122 at each leg but across leg to leg only had 210.

I checked continuity throughout wires from motor and it showed coninuity and I checked the run cap as well, all was good but the motor would not spin. Low voltage was present as well.

This is the furr down in question.


And this is the condenser which was hanging on the outside closet wall of the high rise condo attached to said furrdown, both on one double 40 pole breaker.

The condenser would come on, both compressor and fan, but the inside unit would not.

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Old 09-09-2011, 04:27 PM   #2
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A few questions.


1-Refrigerant escapes from a leak if the system is on or not.
2-Can't remember exactly but it's in the mid 180's .

Bad motor and a leak repair adds up to more then that thing is worth. Still the customers choice on what they want to do though.

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Old 09-09-2011, 04:59 PM   #3
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A few questions.


Refrigerant moves from high pressure to low pressure. The pressure inside the linesets will be high than outside. So It's gonna leak slowly.

Look like the voltage is ok.
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Old 09-09-2011, 05:02 PM   #4
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A few questions.


Make sure the transformer is set to 208 not 230. There's usually a tap by the leads.

It leaks faster proportionally at higher pressures (like summer temp=pressure)
But time added in will mean ur gonna be frozen at start up in spring :$

Last edited by Dr.HVAC; 09-09-2011 at 05:05 PM.
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Old 09-09-2011, 05:03 PM   #5
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A few questions.


Quote:
Originally Posted by Marty S. View Post
1-Refrigerant escapes from a leak if the system is on or not.
2-Can't remember exactly but it's in the mid 180's .

Bad motor and a leak repair adds up to more then that thing is worth. Still the customers choice on what they want to do though.
I was thinking something along the lines of the oils seperating and sitting on the bottom of the coils. Possible, like stacking?
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Old 09-09-2011, 05:06 PM   #6
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A few questions.


Quote:
Originally Posted by Dr.HVAC View Post
Make sure the transformer is set to 208 not 230. There's usually a tap by the leads.

It leaks faster proportionally at higher pressures (like summer temp=pressure)
But time added in will mean ur gonna be frozen at start up

It is a 240 step down transformer and in all honesty I think the motor is bad. I said I tested continuity and I did but between the fan wire to the run cap and the run wire from motor there was nothing. That's it, isn't it?

There was continuity between the run and the common from the motor.
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Old 09-09-2011, 05:08 PM   #7
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A few questions.


Which leads and were they disconnected? A grounded motor would have thrown the breaker

Last edited by Dr.HVAC; 09-09-2011 at 05:12 PM.
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Old 09-09-2011, 05:13 PM   #8
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A few questions.


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Originally Posted by JJboy View Post
Refrigerant moves from high pressure to low pressure. The pressure inside the linesets will be high than outside. So It's gonna leak slowly.

Look like the voltage is ok.

My boss said that as well, saying there's a minimum votage to crank the motor over and 210 volts should do it and I thought as much as I've been down this road before BUT... don't tell anyone, I just wanted to go home so I told her to get an electrician and if that doesn't fix it then I'll be back to replace the motor.

She said she never uses the system as she's rarely ever and she does have another system which works perfectly (one system for one side of the loft and one system for the other side, split left and right), but I'll be back to replace the motor.

I had a strong hunch it wasn't the voltage, I was just kind of hoping.

Also, her 5 microfarad run cap which was plus 10% minus 5% was reading at 4.1, well below the -5% so I installed a new one in the hopes that might work but still nothing.
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Old 09-09-2011, 05:15 PM   #9
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A few questions.


remove motor wires, cap and motor will act like inductor.....
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Old 09-09-2011, 05:22 PM   #10
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A few questions.


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Originally Posted by Dr.HVAC View Post
Which leads and were they disconnected? A grounded motor would have thrown the breaker
Not grounded, open windings. The hot common wire from the breaker in the furr down runs to one side of the fan run cap. From there a common wire from the motor itself is also connected to the cap so now two wires on one side of the cap. There is also a black wire which I want to say comes from the fan delay relay to that common side of the cap. Then there is the fan wire from motor itself that connects to the other side of the run cap.

Between that other single wire on the other side of the cap and either the run (black speed tap wire) or common from motor there was no continuity.

Between the yellow common and the black "run", both from the motor, there is continuity.

There should be continuity between any and all wires coming from the blower motor, showing windings in tact.
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Old 09-09-2011, 05:23 PM   #11
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A few questions.


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Originally Posted by JJboy View Post
remove motor wires, cap and motor will act like inductor.....

Could you explain further, please?.
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Old 09-09-2011, 05:23 PM   #12
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A few questions.


I mean the inductor part. I did remove all wires and test between them.
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Old 09-09-2011, 05:35 PM   #13
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A few questions.


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I mean the inductor part. I did remove all wires and test between them.
You're talking about my nine volt battery in my meter creating the magnetic field in the copper windings, right JJboy?
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Old 09-09-2011, 05:36 PM   #14
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A few questions.


Quote:
Originally Posted by Doc Holliday View Post
I mean the inductor part. I did remove all wires and test between them.

This is the proper way to test continuity.

When testing continuity that has other components in series or parallel .... It creates effects such as resistance, capacitance or inductance
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Old 09-09-2011, 05:37 PM   #15
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A few questions.


Quote:
Originally Posted by JJboy View Post
This is the proper way to test continuity.

When testing continuity that has other components in series or parallel .... It creates effects such as resistance, capacitance or inductance

Yup, I even went to school for this. Doh!

http://www.tabtronics.com/TECHNOLOGY...9/Default.aspx

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